A role for Rhesus factor Rhcg in renal ammonium excretion and male fertility

Nature. 2008 Nov 20;456(7220):339-43. doi: 10.1038/nature07518.

Abstract

The kidney has an important role in the regulation of acid-base homeostasis. Renal ammonium production and excretion are essential for net acid excretion under basal conditions and during metabolic acidosis. Ammonium is secreted into the urine by the collecting duct, a distal nephron segment where ammonium transport is believed to occur by non-ionic NH(3) diffusion coupled to H(+) secretion. Here we show that this process is largely dependent on the Rhesus factor Rhcg. Mice lacking Rhcg have abnormal urinary acidification due to impaired ammonium excretion on acid loading-a feature of distal renal tubular acidosis. In vitro microperfused collecting ducts of Rhcg(-/-) acid-loaded mice show reduced apical permeability to NH(3) and impaired transepithelial NH(3) transport. Furthermore, Rhcg is localized in epididymal epithelial cells and is required for normal fertility and epididymal fluid pH. We anticipate a critical role for Rhcg in ammonium handling and pH homeostasis both in the kidney and the male reproductive tract.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acidosis / physiopathology
  • Acids / metabolism
  • Animals
  • Biological Transport
  • Body Fluids
  • Cation Transport Proteins / deficiency
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Epithelial Cells / metabolism
  • Fertility / physiology*
  • Gene Deletion
  • Genitalia, Male / cytology
  • Genitalia, Male / metabolism
  • Homeostasis
  • Hydrogen-Ion Concentration
  • Kidney / physiology*
  • Kidney Tubules, Collecting / physiology
  • Kidney Tubules, Distal / physiology
  • Male
  • Membrane Glycoproteins / deficiency
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Mice
  • Permeability
  • Quaternary Ammonium Compounds / urine*
  • Stress, Physiological
  • Weight Loss

Substances

  • Acids
  • Cation Transport Proteins
  • Membrane Glycoproteins
  • Quaternary Ammonium Compounds
  • Rhcg protein, mouse